Utility of the Korean Version of Systemic Lupus Activity Questionnaire, in Clinical Practice: Its Correlation with Disease Activity Indices of Systemic Lupus Erythematosus

Abstract

Background/Purpose: Assessing patient-reported outcomes validated to be associated with disease activity has helped clinicians better understand treatment response of patients with systemic rheumatic disease. Such questionnaire for systemic lupus erythematosus (SLE) are rarely used in daily practice; the utility of out-patient targeted questionnaire for SLE has never been studied in Korea.

Methods: The Systemic Lupus Activity Questionnaire, or SLAQ, was translated in Korean (K-) and back-translated, then reviewed by a committee specifically organized for this purpose. This K-SLAQ was then applied to SLE patients followed (out-patient) at institute 1 (SMG-SNU); SELENA-SLEDAI and Systemic Lupus Activity Measure (SLAM)-R was measured on the same day. K-SLAQ was measured again 2 weeks later to assess its reliability. Finally, K-SLAQ was validated in the same manner at a separate institute (2, SNUH). The receiver operating characteristic (ROC) curve was obtained to study K-SLAQ cut-off values in relation to those indicating high disease activity in SELENA-SLEDAI and SLAM-R.

Results: Forty-two patients were enrolled at institute 1, where the median (min-max) age of patients were 40 (19-70), and disease duration was 3.0 (0-18.1) years. The mean K-SLAQ, SELENA-SLEDAI, SLAM-R values were 10 (10-29), 7 (0-26), 5 (1-18), respectively. The correlation between K-SLAQ and the disease activity indices are depicted in the presented table. These results were validated at institute 2 (N= 44). The interclass correlation between repeated K-SLAQ measures was 0.912 (95% CI 0.847-0.949, p< 0.0001), and the area under the ROC curve of SLAQ for SELENA-SLEDAI ©ø 6 was 0.705 (95% CI 0.59-0.82, p= 0.002), and SLAM-R ©ø 7 was 0.704 (95% CI 0.595-0.812, p= 0.001).

Conclusion: K-SLAQ is a useful tool which correlated well with commonly used SLE disease activity indices. This may also facilitate identifying key determinants of flares in daily clinical practice.